html, body {
    height: 100%;
}

body {
    background: url(./images/01.png) no-repeat 50% 0;
    background-size: auto auto;
}

* {
    margin: 0;
    padding: 0;
}

div.content {
    width: 600px;
    height: 100px;
    background-color: aqua;
    position: absolute;
    top: 30%;
    left: 50%;
    transform: translate(-50%, -50%);
    border: 2px solid white;
}

div.pic1, div.pic2, div.pic3 {
    float: left;
    height: 100%;
    width: 200px;
    background-color: blueviolet;
}

div.pic1 {
    background: url(./images/01.png) no-repeat 0 0;
    background-size: 100% auto;
}

div.pic2 {
    background: url(./images/02.png) no-repeat 0 0;
    background-size: 100% auto;
}

div.pic3 {
    background: url(./images/03.png) no-repeat 0 0;
    background-size: 100% auto;
}